U.S. patent application number 14/728198 was filed with the patent office on 2015-12-10 for method of regulating an internal combustion engine.
The applicant listed for this patent is GE Jenbacher GmbH & Co OG. Invention is credited to Herbert KOPECEK, Nikolaus SPYRA, Michael WALDHART.
Application Number | 20150354471 14/728198 |
Document ID | / |
Family ID | 53396203 |
Filed Date | 2015-12-10 |
United States Patent
Application |
20150354471 |
Kind Code |
A1 |
KOPECEK; Herbert ; et
al. |
December 10, 2015 |
METHOD OF REGULATING AN INTERNAL COMBUSTION ENGINE
Abstract
A method of regulating an internal combustion engine (1) having
more than one cylinder (2), wherein individual cylinders (2) can be
deactivated in accordance with a predeterminable pattern in
dependence on the required power output, wherein the pattern
comprises a time sequence of commands for ignition and commands for
skipping ignition, wherein the pattern is derived with a
calculation specification in such a way that the spacing between
cylinders (2) intended for skipping in relation to the firing order
is an odd number and preferably in coprime relationship with the
number of cylinders.
Inventors: |
KOPECEK; Herbert; (Schwaz,
AT) ; SPYRA; Nikolaus; (Innsbruck, AT) ;
WALDHART; Michael; (Telfs, AT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GE Jenbacher GmbH & Co OG |
Jenbach |
|
AT |
|
|
Family ID: |
53396203 |
Appl. No.: |
14/728198 |
Filed: |
June 2, 2015 |
Current U.S.
Class: |
123/406.2 |
Current CPC
Class: |
F02B 2075/1868 20130101;
F02B 2075/1848 20130101; F02D 2250/18 20130101; F02D 41/008
20130101; F02D 41/0087 20130101; F02D 17/02 20130101 |
International
Class: |
F02D 17/02 20060101
F02D017/02; F02P 5/145 20060101 F02P005/145 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 4, 2014 |
AT |
437/2014 |
Claims
1. A method of regulating an internal combustion engine having more
than one cylinder, wherein individual cylinders can be deactivated
in accordance with a predeterminable pattern in dependence on the
required power output, wherein the pattern comprises a time
sequence of commands for ignition and commands for skipping
ignition, wherein the pattern is derived with a calculation
specification in such a way that the spacing between cylinders
intended for skipping in relation to the firing order is an odd
number and preferably in coprime relationship with the number of
cylinders.
2. A method as set forth in claim 1, wherein the pattern is
described by way of an algorithm in dependence on the number of
cylinders.
3. A method as set forth in claim 1, wherein the pattern is derived
by way of an algorithm from the firing order in such a way that the
commands for ignition are distributed uniformly to the cylinder
banks.
4. A method as set forth in claim 1 wherein the pattern can be
written as a list of commands for ignition followed by commands for
non-ignition, wherein the pattern can be altered in respect of time
such that after a predeterminable time interval there is added to a
predeterminable list position with a command for ignition a number
of at least one further list position with a signal for ignition
and the list portion with commands for non-ignition is supplemented
by the same number of list positions with signals for
non-ignition.
5. A method as set forth in claim 1, wherein the pattern is altered
after a predeterminable time interval, wherein the time interval is
between 1 and 20 seconds, particularly preferably being 5-10
seconds.
6. A method as set forth in claim 1, wherein the variation in
respect of time of the pattern takes place such that as few
cylinders as possible, particularly preferably only one cylinder,
change over from an unfired to a fired state and as few cylinders
as possible change over from a fired to an unfired state.
7. A method as set forth in claim 1, wherein at least one cylinder
remains excluded from cylinder deactivation.
8. A method as set forth in claim 1, wherein the pattern can be
altered in respect of time such that upon an increased power demand
the list block with commands for ignition is prolonged by at least
one further command for ignition.
9. A method as set forth in claim 1, wherein the pattern can be
altered in respect of time such that upon an reduced power demand
the list block with commands for ignition skipping is prolonged by
at least one further command for ignition skipping.
Description
[0001] The present invention concerns a method of regulating an
internal combustion engine having the features of the preamble of
claim 1.
[0002] Methods of cylinder deactivation, referred to in English as
"skip firing", are known from the state of the art. Skip firing is
used predominantly in larger engines with more than six cylinders
in order to reduce the fuel consumption and emissions when there is
a reduced demand for power.
[0003] DE 43 10 261 describes that patterns for selective skip
firing (referred to in the specification as deactivation patterns)
can be predetermined to protect an engine from overloading. The
patterns are advantageously so matched to the number of cylinders
that there are circulating deactivation sequences, that is to say
each cylinder is relieved of load within a very short time.
[0004] It is known from DE 2928075 that the sequence of commands
for ignition and for skip firing is so selected that the internal
combustion engine runs as smoothly as possible, in particular
harmonics of the resonance frequencies of the engine suspension and
the drive train are avoided and the operation of individual
piston-cylinder units does not cease more frequently than between
two and three times so that those piston-cylinder units do not cool
down too greatly.
[0005] Skip firing methods are further known from US2013289853,
US2013298870, U.S. Pat. No. 8,099,224, US2013092128, US2012109495,
U.S. Pat. No. 8,336,521, U.S. Pat. No. 8,131,447 and
US2013092127.
[0006] It has been found in the applicant's tests that presetting
fixed ignition deactivation patterns is detrimental as there is an
uncertainty in respect of time in regulation as to whether an
individual cylinder does or does not receive the signal for
ignition in the next working cycle. Unwanted omission of a cylinder
intended for ignition results in a fall in the speed of the engine
while unwanted ignition of a cylinder intended to be deactivated
leads to an unwanted rise in engine speed.
[0007] It is possible to counteract that uncertainty by a
crankshaft angle-synchronous control. A crankshaft
angle-synchronous control with discrete time presettings for the
ignition timing of each cylinder is however complicated and
expensive.
[0008] Even if a plurality of cylinder deactivation patterns are
predetermined and those patterns are interchanged that has the
disadvantage that when switching over the patterns a plurality of
cylinders make the transition from a fired to an unfired condition
and vice-versa. For thermal reasons however it is disadvantageous
if a cylinder for example fires only once and is then deactivated
again. In addition it is detrimental if a plurality of cylinders
change their status in each cycle (2 crankshaft angle revolutions
corresponding to 720.degree. for 4-stroke engines). Thus in the
transition from one cylinder deactivation pattern to another
pattern, the situation can arise where a plurality of cylinders
which are in succession in their firing sequence are deactivated,
that is to say there is a longer sequence without ignition
events.
[0009] Therefore the object of the invention is to provide an
improved method for the omission of cylinder firings, in which the
thermal load is more uniformly distributed to the cylinders.
[0010] That object is attained by a regulation method having the
features of claim 1. Preferred embodiments are recited in the
appendant claims.
[0011] The fact that the pattern is deduced with a calculation
specification in such a way that the spacing between cylinders
intended for skipping in relation to the ignition sequence is an
odd number and preferably in coprime relationship with the number
of cylinders achieves a more uniform input of heat to all
cylinders.
[0012] In the context of the present disclosure the term "skip" of
cylinders is intended to mean that those cylinders do not have
ignition, which in turn can be implemented by omission of ignition
and/or omission of the fuel feed. The latter is relevant in
particular for internal combustion engines which are equipped with
a fuel feed individually for each cylinder, for example
port-injection valves. The terms "fired" and "unfired" are used
synonymously for "ignited" and "non-ignited" respectively.
[0013] In the proposed method the cylinder deactivation pattern
(referred to in English as the skip firing order) is firstly
derived from the ignition sequence (referred to in English as the
firing order) of the engine in question. In that respect the
procedure is as follows:
[0014] The firing order is a time sequence of the ignition timing
points of the individual cylinders, which is predetermined by the
crank throws of the crankshaft, that is to say mechanically and
invariably for an engine being considered. The firing order is
frequently so selected that it involves an application of the
torques to the crankshaft, that is distributed advantageously in
terms of place and time, the crankshaft as far as possible is not
excited to involve torsional oscillations and, when there are two
cylinder banks, the mutually opposite cylinders fire in
succession.
[0015] In the usual notation the cylinders are numbered in such a
way that, in relation to the drive output side and when there are a
plurality of cylinder banks, the count is begun at the left-hand
cylinder bank. Table 1 shows the numbering of the cylinders of a
V-20 engine in the form of a two-column Table. The left-hand column
with the entries one through ten corresponds to the left-hand
cylinder bank while the right-hand column with the entries eleven
through twenty corresponds to the right-hand cylinder bank.
TABLE-US-00001 TABLE 1 Numbering of the cylinders of a V-20 engine
in the form of a two-column Table: 10 20 9 19 8 18 7 17 6 16 5 15 4
14 3 13 2 12 1 11
[0016] Usual firing orders for in-line engines are:
For six-cylinder in-line engines: 1-5-3-6-2-4 or 1-2-4-6-5-3 or
1-4-2-6-3-5 or 1-4-5-6-3-2. For eight-cylinder in-line engines:
1-6-2-5-8-3-7-4 or 1-3-6-8-4-2-7-5 or 1-4-7-3-8-5-2-6 or
1-3-2-5-8-6-7-4. For V-engines for example the following firing
orders are commonly involved: Six-cylinder engines: 1-4-3-6-2-5 or
1-2-5-6-4-3 or 1-4-5-6-2-3. Twelve-cylinder engines:
1-7-5-11-3-9-6-12-2-8-4-10 or 1-12-4-9-2-11-6-7-3-10-5-8.
[0017] In particular in motor vehicles there are also many further
variants.
[0018] Table 2 shows a typical firing order of a V-20 cylinder
engine. In that respect the first line shows the time sequence of
ignition and the line therebelow shows the number--corresponding to
the above-discussed notation--of the respective cylinder. The
illustrated firing order corresponds to two crankshaft revolutions
in the case of 4-stroke engines and one crankshaft revolution in
the case of 2-stroke engines and begins again from the front end
after the last cylinder.
TABLE-US-00002 TABLE 2 Firing order of a V-20 cylinder engine 1 2 3
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 17 7 13 3 19 9 15 5 20
10 14 4 18 8 12 2 16 6 11 1
[0019] It is preferably provided that the pattern can be described
by way of an algorithm in dependence on the number of
cylinders.
[0020] Starting from the firing order, a skip firing order is
derived such that the cylinders skip in an odd-numbered
sequence.
[0021] It can also be provided that the pattern is derived from the
firing order by way of an algorithm such that the ignition commands
are distributed uniformly to the cylinder banks.
[0022] That can be for example every third or fifth or seventh
cylinder, generally described as two n+1 (2n+1) with n a natural
number. That provides that the omissions are distributed to both
cylinder banks. The choice of a number which is not a divisor of
the number of cylinders is particularly desirable, for example
three for a 20-cylinder engine or five for a 12-cylinder
engine.
[0023] If the series comes again to a cylinder which has already
been taken into consideration in the skip firing order, that is to
say omitted, then that situation involves a departure from the rule
and the method goes forward or back from that cylinder, to the next
cylinder which was not yet taken into consideration in the skip
firing order. The cylinder following same and intended for
deactivation is again established with the above-defined rule. It
will be appreciated that the skip firing order can be begun at any
desired cylinder.
[0024] Thus with the rule with (2n+1)=3, from the firing order of a
V-12 cylinder engine, which reads: 1-7-5-11-3-9-6-12-2-8-4-10, that
gives the skip firing order 1-11-6-8-7-3-12-4-5-9-2-10.
[0025] In a further example, the spacing 5, that is to say the
fifth cylinder after the last one, is adopted as the rule for
selection of the cylinder to be skipped.
[0026] From the firing order 1-7-5-11-3-9-6-12-2-8-4-10 that gives
the following skip firing order: 1-9-4-11-2-7-6-10-3-8-5-12.
[0027] The pattern is now varied in respect of time for
distribution of the load to the cylinders, in uniform relationship
in respect of time:
[0028] It can preferably be provided that, after a predeterminable
time interval, there is added to a predeterminable list position
with a command for ignition a number of at least one further list
position with a signal for ignition and the list portion with
commands for non-ignition is supplemented by the equal number of
list positions with signals for non-ignition. List or list position
means the following: the ignition deactivation pattern or skip
firing order can be constituted as a list of commands for ignition,
represented by a one, and commands for skip (non-ignition),
represented by a zero. That will be illustrated by means of the
Table hereinafter. Thus Table 3 in the first line shows the skip
firing order in relation to the cylinder in question, and the line
underneath shows the skip commands, represented by a zero, and the
ignition commands, represented by a one. In the specific example
cylinders 11, 2 and 18 receive the skip command, followed by the
cylinders 10, 15, 3, 17, 6, 12, 4, 20, 9 with ignition command,
followed by cylinders 13, 16, 8, 14, 5, 19 and 7 with skip command.
Skipping is therefore reproduced in the list by a zero while
ignition is signaled by a one.
[0029] The variation in the skip firing order in respect of time is
now effected in such a way that there is added to a predeterminable
list position with a command for ignition at least one further list
position with a signal for ignition and the subsequent block of
commands for non-ignition is supplemented by at least one further
list position with a signal for non-ignition. In the specific
example that is shown in line 3 of Table 4: cylinder 13 changes
from non-ignition to ignition while cylinder 10 changes from the
ignited to the non-ignited state.
TABLE-US-00003 TABLE 3 Skip firing order stored with commands for
skip (zeros) and ignition (ones) 11 2 18 10 15 3 17 6 12 4 20 9 13
16 8 14 5 19 7 0 0 0 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 1 1 1
1 1 1 1 1 1 0 0 0 0 0 0
[0030] Distribution of the load to the cylinders, which is uniform
in respect of time, is therefore effected by the list entry with
the firing commands being prolonged by an increment while at the
same time the list entry with ignition skip commands is also
increased by the same increment.
[0031] This therefore involves a displacement of the ignition
commands by the selectable increment. That can include for example
one or also more cylinders.
[0032] The displacement of the ignition commands by a selectable
increment provides that the sequence, or in other words the list
portion, with commands for ignition in operation of the internal
combustion engine "travels", that is to say moves over all
cylinders.
[0033] In a very simple fashion that affords a possible way of
uniformly distributing the load and heat input to the engine.
[0034] In a preferred configuration it is provided that the pattern
is altered after a predeterminable time interval, wherein the time
interval is between 1 and 20 seconds, particularly preferably being
5-10 seconds. In other words the firing pattern remains unchanged
for 1-20 seconds, particularly preferably 5-10 seconds.
[0035] It is preferably provided that the variation in respect of
time of the pattern takes place such that as few cylinders as
possible, particularly preferably only one cylinder, change over
from an unfired to a fired state and as few cylinders as possible
change over from a fired to an unfired state. As stated in the
opening part of this specification it is desirable for thermal
reasons if, in a period of time under consideration, as few
cylinders as possible and preferably only one cylinder change their
firing status.
[0036] It can preferably be provided that at least one cylinder
remains excluded from cylinder skipping. For example for diagnostic
purposes, for example by instrumentation of a cylinder, it may be
an aspect of interest for that cylinder to be excluded from
cylinder deactivation.
[0037] In deriving the skip firing order for that purpose the
cylinders to be excluded are removed from the firing order and then
the above-described method for determining the skip firing order is
carried out with the reduced firing order. That is illustrated in
Table 4. Table 4 shows the reduced firing order of a V-20 cylinder
engine wherein the last position, that is to say cylinder number
one was deactivated. In that respect the first line shows the time
sequence of ignition and the line underneath shows the number of
the respective cylinder. It will be appreciated that cylinder one
is not really excluded from ignition, but only from the list for
ascertaining the cylinders to be skipped. As there are only still
nineteen cylinders remaining in the reduced firing order the step
length of five is sufficient, which would in fact be a divisor of
the number of cylinders for the 20-cylinder engine.
TABLE-US-00004 TABLE 4 Reduced firing order of a V-20 cylinder
engine, cylinder one is excluded 1 2 3 4 5 6 7 8 9 10 11 12 13 14
15 16 17 18 19 17 7 13 3 19 9 15 5 20 10 14 4 18 8 12 2 16 6 11
[0038] If now the rule for ignition skipping is applied to the
reduced firing order then cylinder one remains excluded from
ignition skipping. In other words therefore cylinder one is quite
regularly fired.
[0039] The result is intended to be explained using the example of
the reduced firing order of Table 4. In that case the rule of
skipping after each third cylinder is applied to the firing order
of Table 4. To make it clear that the direction of the ascertaining
operation (therefore in the list from left to right or from right
to left) and the starting position for the ascertaining operation
are immaterial, the procedure is begun at cylinder eleven and moved
from right to left. That is to say, after eleven there comes two,
after that 18, then ten and so forth. The result, that is to say
the skip firing order of the reduced firing order, is shown in
Table 5. The resulting skip firing order for the 20-cylinder engine
has only 19 entries as in fact a cylinder is excluded from ignition
skipping.
TABLE-US-00005 TABLE 5 Skip firing order of the reduced firing
order of a V-20 cylinder engine 11 2 18 10 15 3 17 6 12 4 20 9 13
16 8 14 5 19 7
[0040] That skip firing order however is still not adapted to a
specific load demand but only describes the sequence which is to be
followed in cylinder skipping.
[0041] The proposed method now involves superposing on the skip
firing order obtained, a further pattern establishing which of the
cylinders defined in the skip firing order are actually intended
for non-ignition.
[0042] That pattern can be constituted as a list or sequence of
commands for non-ignition, expressed by a zero, followed by list
entries with a one, for the command for ignition.
[0043] If now that pattern is superposed with the previously
established skip firing order then the number of cylinders actually
to be skipped can be established and thus adapted to a load demand.
The method will be illustrated with Table 6 hereinafter. Table 6
again follows the example of the reduced firing order, wherein the
cylinder one is excluded from skipping. That can be provided for
example for diagnostic purposes or the like. The load demand will
be assumed in the example such that ten of the twenty cylinders are
to have ignition. Thus Table 6 in the first line shows the ignition
deactivation pattern or skip firing order in relation to the
cylinder in question, and the line underneath shows the commands
for skipping, represented by a zero, and the commands for ignition,
represented by a one, respectively. In the specific example
cylinders 11, 2 and 18 receive the command for skipping, followed
by the cylinders 10, 15, 3, 17, 6, 12, 4, 20, 9 with the command
for ignition, followed by the cylinders 13, 16, 8, 14, 5, 19 and 7
with the command for skipping. Skipping is therefore reproduced in
the list by a zero while ignition is signaled by a one.
TABLE-US-00006 TABLE 6 Skip firing order stored with commands for
skipping (zeros) and ignition (ones) 11 2 18 10 15 3 17 6 12 4 20 9
13 16 8 14 5 19 7 0 0 0 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0
[0044] Illustrated in the form of list entries, that therefore
gives a sequence of entries with signal for ignition, represented
by ones, followed by a list portion with the information relating
to ignition skipping, shown by zeros. It will already be seen from
the example for Table 6 that it is very easily possible in that way
to establish the proportion of those cylinders which are intended
to continue to have ignition, in other words, for what load
proportion the engine is to be operated. In the example of Table 6
ten out of twenty cylinders have ignition, that is to say the load
reduction is around 50%.
[0045] Particularly preferably it can be provided that, with an
increased power requirement, the list block with commands for
ignition is prolonged by at least one further command for
ignition.
[0046] If therefore the load demand rises that can easily be
achieved by prolonging the list portion with signals for ignition
by a further increment. Increment means at least one list
entry.
[0047] Table 7 shows for example that the list portion with
commands for ignition, that is to say list entries with one, is
increased by a further list position. In the specific example
cylinder 13 is now also intended for ignition.
TABLE-US-00007 TABLE 7 11 2 18 10 15 3 17 6 12 4 20 9 13 16 8 14 5
19 7 0 0 0 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0
[0048] In that way the number of fired cylinders is increased to
eleven while nine cylinders remain unfired.
[0049] It is preferably provided that the pattern can be altered in
respect of time such that upon an reduced power demand the list
block with commands for ignition skipping is prolonged by at least
one further command for ignition skipping.
[0050] Table 8 shows that situation. Here the sequence of
non-ignitions is prolonged by a further list entry so that now
eleven cylinders do not have ignition and nine cylinders involve
ignition. It is thus possible to achieve a further power reduction.
In the specific case, in comparison with the starting condition, as
shown in Table 6, cylinder number ten additionally skips.
TABLE-US-00008 TABLE 8 11 2 18 10 15 3 17 6 12 4 20 9 13 16 8 14 5
19 7 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0
[0051] The specified examples show the situation which is unchanged
in respect of time, that is to say always the same cylinders have
ignition while the remaining cylinders remain unfired. As described
hereinbefore, the pattern is altered in respect of time for
distribution of the load to the cylinders, uniformly in respect of
time.
[0052] If the firing order is envisaged as a closed circle in which
the last-ignited cylinder adjoins the first-ignited cylinder then
the block of ignited cylinders now rotates in the circle.
[0053] The invention will now be described in greater detail with
reference to the Figures in which:
[0054] FIG. 1 diagrammatically shows an internal combustion engine
of the general kind involved, and
[0055] FIG. 2 shows a representation of the firing order in the
form of a closed circle.
[0056] FIG. 1 diagrammatically shows a plan view of an internal
combustion engine 1. The piston-cylinder units 2 are indicated. The
Figure serves to explain the notation with which the cylinders are
identified: the arrow symbolizes the direction of view, looking
therefore on to the side opposite to the drive output end,
identified as G, where counting is begun. The cylinder number one
is on the cylinder bank at the left in the direction of view. The
Figure shows a V-16 cylinder engine.
[0057] FIG. 2 serves to illustrate the concept of the rotating skip
firing order and shows the firing order in the form of a closed
circle, using the example of a 20-cylinder engine in which cylinder
number one is excluded from ignition skipping, that is to say it
fires regularly. The digits in the fields correspond to the number
of the respective cylinder. The fields colored black show ignited
cylinders while the white fields show non-ignited cylinders. The
sequence of the cylinders corresponds to the skip firing order. The
arrows between the fields symbolize the firing order in respect of
time.
[0058] The block with commands for ignition travels in the circle
due to the alteration in respect of time of the skip firing
pattern. That is clearly identified by the details D1 and D2. Thus
for example cylinder number ten receives the command for
non-ignition (detail D1) and therefore changes its status from
ignition to skip. Subsequently cylinder 13 changes from the
condition unfired by the ignition to the fired condition (detail
D2). Thus the number of fired and unfired cylinders respectively
remains constant, but the pattern "travels" over the cylinders,
thereby giving a uniform input of heat to the cylinders.
* * * * *